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<html lang="zh-CN">
    <head>
        <meta charset="UTF-8" />
        <title>04_基本数据类型-高级-null</title>
    </head>
    <body>
        <script>
            // null一般用于删除对象 
            // undefined是派生于null  undefined是null的子类
            console.log(undefined == null);
            console.log(null == undefined);
        </script>
    </body>
</html>